Copper electroplating solution, method of producing same, and copper electroplating method

ABSTRACT

The present invention provides a copper electroplating solution including: (A) a sulfate ion; (B) a compound represented by the following general formula (1); and (C) a copper ion, wherein the copper electroplating solution has a content of the component (B) of from 0.3 part by mass to 50 parts by mass and a content of the component (C) of from 5 parts by mass to 50 parts by mass with respect to 100 parts by mass of a content of the component (A): 
     
       
         
         
             
             
         
       
     
     where R 1  and R 2  each independently represent a hydrogen atom, a sodium atom, a potassium atom, or an alkyl group having 1 to 5 carbon atoms, and “n” represents 1 or 2, a method of producing the copper electroplating solution, and a copper electroplating method including using the copper electroplating solution.

TECHNICAL FIELD

The present invention relates to a copper electroplating solutioncomprising sulfuric acid and a compound having a specific structure, amethod of producing the copper electroplating solution, and to a copperelectroplating method comprising using the copper electroplatingsolution.

BACKGROUND ART

In the formation of a fine wiring, a through silicon via (TSV), and abump in a highly integrated electronic circuit, an approach involvingfilling a metal in a pattern, such as a groove or a hole, has heretoforebeen used. Copper electroplating is one typical approach involvingfilling a metal. Of such approaches, copper electroplating involvingfilling copper as a metal has been widely used. In the formation of acircuit by the copper electroplating, it is required that a copper layerhaving a high purity and satisfactory surface flatness be formed inorder to obtain high connection reliability.

As a copper electroplating solution that has heretofore been known, forexample, in Patent Literature 1, there is a disclosure of a copperplating bath containing 0.8 M copper sulfate and 0.5 M isethionic acid.In addition, in Patent Literature 2, there is a disclosure of a copperplating bath containing copper oxide and isethionic acid, and in PatentLiterature 3, there is a disclosure of a copper plating bath containingcopper sulfate pentahydrate, sulfuric acid, hydrochloric acid, and atrace amount of isethionic acid.

CITATION LIST Patent Literature

-   [PTL 1] JP 2006-199994 A-   [PTL 2] JP 2006-265632 A-   [PTL 3] JP 2007-016264 A

SUMMARY OF INVENTION Technical Problem

However, when copper electroplating is performed with each of the copperelectroplating solutions as described in Patent Literatures 1 to 3above, there have been problems in that a copper layer excellent insurface flatness cannot be obtained, and further, a copper layer to beobtained has a low purity. Accordingly, an object of the presentinvention is to provide a copper electroplating solution capable ofproviding a copper layer that has a high purity and is excellent insurface flatness.

Solution to Problem

The inventors of the present invention made investigations, and as aresult, found that the above-mentioned object can be achieved by using acopper electroplating solution comprising a sulfate ion, a copper ion,and a compound having a specific structure at predetermined blendingratios. Thus, the inventors completed the present invention.

That is, according to one embodiment of the present invention, there isprovided a copper electroplating solution, comprising the followingcomponents: (A) a sulfate ion; (B) a compound represented by thefollowing general formula (1); and (C) a copper ion, wherein the copperelectroplating solution has a content of the component (B) of from 0.3part by mass to 50 parts by mass and a content of the component (C) offrom 5 parts by mass to 50 parts by mass with respect to 100 parts bymass of a content of the component (A):

where R¹ and R² each independently represent a hydrogen atom, a sodiumatom, a potassium atom, or an alkyl group having 1 to 5 carbon atoms,and “n” represents 1 or 2.

In addition, according to one embodiment of the present invention, thereis provided a copper electroplating method comprising using theabove-mentioned copper electroplating solution.

Advantageous Effects of Invention

According to the copper electroplating solution of the presentinvention, the copper layer that has a high purity and is excellent insurface flatness can be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of a substrate to be plated afterthe formation of a copper layer on the surface of the substrate to beplated by a copper electroplating method in an evaluation test.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are described in detail below.

<Copper Electroplating Solution>

A copper electroplating solution of the present invention is a copperelectroplating solution containing, as essential components, thefollowing components: (A) a sulfate ion (hereinafter also referred to as“component (A)”); (B) a compound represented by the general formula (1)(hereinafter also referred to as “component (B)”); and (C) a copper ion(hereinafter also referred to as “component (C)”).

A supply source for the component (A) (sulfate ion) is not particularlylimited, but for example, at least one kind selected from the groupconsisting of: sulfuric acid; copper sulfate; iron sulfate; leadsulfate; silver sulfate; calcium sulfate; potassium sulfate; sodiumsulfate; barium sulfate; magnesium sulfate; aluminum sulfate; nickelsulfate; a mixture thereof; and a hydrate thereof may be used. Thosesupply sources for the component (A) may be used alone or in combinationthereof. The supply source for the component (A) to be used ispreferably at least one kind of sulfuric acid, copper sulfate, or coppersulfate pentahydrate, more preferably a combination of sulfuric acid andcopper sulfate or copper sulfate pentahydrate because a copper layerthat has a higher purity and is excellent in surface flatness can beobtained.

The component (B) is a compound represented by the following generalformula (1):

where R¹ and R² each independently represent a hydrogen atom, a sodiumatom, a potassium atom, or an alkyl group having 1 to 5 carbon atoms,and “n” represents 1 or 2.

In the general formula (1), R¹ and R² each independently represent ahydrogen atom, a sodium atom, a potassium atom, or an alkyl group having1 to 5 carbon atoms. Examples of the alkyl group having 1 to 5 carbonatoms represented by each of R¹ and R² may include a methyl group, anethyl group, a propyl group, an isopropyl group, a butyl group, anisobutyl group, a secondary butyl group, a tertiary butyl group, apentyl group, and a neopentyl group. R¹ preferably represents a hydrogenatom or a sodium atom, and more preferably represents a hydrogen atombecause a copper layer that is more excellent in surface flatness can beobtained. R² preferably represents a hydrogen atom.

In the general formula (1), “n” represents 1 or 2. “n” preferablyrepresents 2 because a copper layer that is more excellent in surfaceflatness can be obtained.

Preferred specific examples of the compound represented by the generalformula (1) include the following compounds No. 1 to No. 12. In thefollowing compounds, the symbol “Me” represents a methyl group, thesymbol “Et” represents an ethyl group, and the symbol “iPr” representsan isopropyl group.

Of the above-mentioned compounds, the compounds No. 2, No. 7, and No. 8are preferred, and the compound No. 7 is more preferred.

A supply source for the component (C) (copper ion) is not particularlylimited, but for example, at least one kind selected from the groupconsisting of: copper sulfate; copper chloride; copper bromide; copperhydroxide; a mixture thereof; and a hydrate thereof may be used. Thosesupply sources for the component (C) may be used alone or in combinationthereof. The supply source for the component (C) to be used ispreferably copper sulfate or copper sulfate pentahydrate because acopper layer that has a higher purity and is excellent in surfaceflatness can be obtained.

The content of the component (B) in the copper electroplating solutionis from 0.3 part by mass to 50 parts by mass with respect to 100 partsby mass of the content of the component (A). The content of thecomponent (B) is preferably from 1 part by mass to 30 parts by mass,more preferably from 3 parts by mass to 20 parts by mass with respect to100 parts by mass of the content of the component (A) because a copperlayer that is more excellent in surface flatness can be obtained.

The content of the component (C) in the copper electroplating solutionis from 5 parts by mass to 50 parts by mass with respect to 100 parts bymass of the content of the component (A). The content of the component(C) is preferably from 10 parts by mass to 40 parts by mass, morepreferably from 20 parts by mass to 30 parts by mass with respect to 100parts by mass of the content of the component (A) because a copper layerthat has a higher purity and is excellent in surface flatness can beobtained. The content of the component (B) is preferably from 1 part bymass to 200 parts by mass, more preferably from 5 parts by mass to 100parts by mass, most preferably from 10 parts by mass to 70 parts by masswith respect to 100 parts by mass of the content of the component (C)because a copper layer that has a higher purity and is excellent insurface flatness can be obtained.

The concentration of the component (A) (sulfate ion) in the copperelectroplating solution is not particularly limited, but is generallyfrom 10 g/L to 500 g/L, preferably from 50 g/L to 350 g/L, morepreferably from 100 g/L to 250 g/L, still more preferably from 110 g/Lto 200 g/L.

The concentration of the component (B) in the copper electroplatingsolution is not particularly limited, but is generally from 0.3 g/L to80 g/L, preferably from 1 g/L to 60 g/L, more preferably from 5 g/L to40 g/L, still more preferably from 5 g/L to 35 g/L.

The concentration of the component (C) in the copper electroplatingsolution is not particularly limited, but is generally from 5 g/L to 250g/L, preferably from 10 g/L to 150 g/L, more preferably from 20 g/L to80 g/L, still more preferably from 25 g/L to 70 g/L.

The copper electroplating solution of the present invention may contain,as a component except the above-mentioned component (A) to component(C), a chloride ion source, a plating promoter, a plating inhibitor, orthe like

The chloride ion source is not particularly limited, but examplesthereof include hydrogen chloride and sodium chloride. The concentrationof the chloride ion source in the copper electroplating solution ispreferably from 5 mg/L to 200 mg/L, more preferably from 20 mg/L to 150mg/L.

The plating promoter is not particularly limited, but examples thereofinclude compounds represented by the following general formulae (2) to(4).

XO₃S—R—SH  (2)

XO₃—Ar—S—S—Ar—SO₃X  (3)

In the general formulae (2) and (3), R represents a substituted orunsubstituted alkyl group, preferably an alkyl group having 1 to 6carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms,Ar represents a substituted or unsubstituted aryl group, such as asubstituted or unsubstituted phenyl group or naphthyl group, and Xrepresents a counterion, such as a sodium or potassium ion.

In the general formula (4), R²¹ and R²² each represent a hydrogen atom,a linear or branched alkyl group having 1 to 6 carbon atoms, acycloalkyl group having 5 to 9 carbon atoms that may have a substituenthaving 1 to 3 carbon atoms, or an aryl group that may have a substituenthaving 1 to 3 carbon atoms, M represents an alkali metal, ammonium, or amonovalent organic ammonium, and “n” represents a number of from 1 to 7.

Of those described above, sodium 3,3′-dithiobis(1-propanesulfonate)(hereinafter sometimes abbreviated as “SPS”) is preferred as the platingpromoter from the viewpoint that SPS has a high promoting effect on theformation of a copper layer.

The concentration of such plating promoter in the copper electroplatingsolution is preferably from 0.1 mg/L to 100 mg/L, more preferably from0.5 mg/L to 50 mg/L, most preferably from 1 mg/L to 30 mg/L.

For example, an oxygen atom-containing high-molecular weight organiccompound may be used as the plating inhibitor. Specific examples thereofinclude polyethylene glycol, polypropylene glycol, apolyoxyethylene-polyoxypropylene random copolymer, and apolyoxyethylene-polyoxypropylene block copolymer. Of those, polyethyleneglycol is preferred. From the viewpoint of further improving the effectof the present invention, the molecular weight of such oxygenatom-containing high-molecular weight organic compound is preferablyfrom 500 to 100,000, more preferably from 1,000 to 10,000. Inparticular, polyethylene glycol having a molecular weight of from 1,000to 10,000 is most preferred. From the same viewpoint, the concentrationof the oxygen atom-containing high-molecular weight organic compound inthe copper electroplating solution is preferably from 50 mg/L to 5,000mg/L, more preferably from 100 mg/L to 3,000 mg/L.

In the present invention, a well-known solvent may be used as a solventfor the copper electroplating solution. Examples of the solvent include:water; alcohols, such as methanol, ethanol, isopropyl alcohol, andn-butanol; acetic acid esters, such as ethyl acetate, butyl acetate, andmethoxyethyl acetate; ethers, such as tetrahydrofuran, tetrahydropyran,ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,triethylene glycol dimethyl ether, dibutyl ether, and dioxane; ketones,such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone,dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone,and methylcyclohexanone; and hydrocarbons, such as hexane, cyclohexane,methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane,octane, toluene, and xylene. Those solvents may be used alone or incombination thereof.

Of those solvents, water and alcohols are preferred, and water is morepreferred.

Any other additive known to be capable of being added to a platingsolution may be optionally used in the copper electroplating solution ofthe present invention to the extent that the effect of the presentinvention is not inhibited.

Examples of the other additive include an anthraquinone derivative, acationic surfactant, a nonionic surfactant, an anionic surfactant, anamphoteric surfactant, an alkanesulfonic acid, an alkanesulfonic acidsalt, an alkanesulfonic acid ester, a hydroxyalkanesulfonic acid ester,and a hydroxyalkanesulfonic acid organic acid ester (provided that acompound corresponding to the component (B) of the present invention isexcluded). The concentration of such other additive in the copperelectroplating solution is preferably from 0.1 mg/L to 500 mg/L, morepreferably from 0.5 mg/L to 100 mg/L.

The pH of the copper electroplating solution is not particularlylimited, but generally acidic conditions of pH 4 or less, preferablyacidic conditions of pH 3 or less, and more preferably strong acidicconditions of pH 2 or less are adopted. For the measurement of the pH, apH meter LAQUA F-70 manufactured by HORIBA, Ltd. or the like may beused. A temperature at the time of the measurement of the pH may beabout room temperature.

<Copper Electroplating Method>

Next, a copper electroplating method comprising using the copperelectroplating solution of the present invention is described. Thecopper electroplating method of the present invention may be performedin the same manner as a related-art copper electroplating method exceptthat the copper electroplating solution of the present invention is usedas a copper electroplating solution. Herein, a copper electroplatingmethod comprising forming a copper layer on a substrate to be plated isdescribed.

For example, a paddle stirring-type plating apparatus only needs to beused as a copper electroplating apparatus. The plating tank of thecopper electroplating apparatus is filled with the copper electroplatingsolution of the present invention, and the substrate to be plated isimmersed in the copper electroplating solution. For example, a productobtained by forming a resist pattern on a Si substrate with a copperseed layer through use of a photoresist may be used as the substrate tobe plated.

At this time, for example, the temperature of the copper electroplatingsolution is from 10° C. to 70° C., preferably from 20° C. to 60° C., anda current density falls within the range of from 1 A/dm² to 70 A/dm²,preferably from 5 A/dm² to 50 A/dm², more preferably from 15 A/dm² to 35A/dm². In addition, for example, air stirring, quick liquid currentstirring, or mechanical stirring with a stirring blade or the like maybe used as a method of stirring the copper electroplating solution.

When copper is filled in an opening portion of the resist pattern undersuch conditions as described above, a copper layer that has a highpurity and is excellent in surface flatness can be formed on thesubstrate to be plated.

A plated product to be manufactured by using the copper electroplatingmethod of the present invention is not particularly limited, andexamples thereof include a wide range of products, such as materials forautomobile industry (such as a heat sink, a carburetor part, a fuelinjector, a cylinder, various valves, and an inner part of an engine),materials for electronic industry (such as contact, a circuit, asemiconductor package, a printed board, a film resistor, a capacitor, ahard disk, a magnetic material, a lead frame, a nut, a magnet, aresistor, a stem, a computer part, an electronic part, a laseroscillation device, an optical memory device, an optical fiber, afilter, a thermistor, a heater, a heater for high temperature, avaristor, a magnetic head, various sensors (gas, temperature, humidity,light, speed, and the like), and MEMS), precision instruments (such as acopying machine part, an optical instrument part, and a timepiece part),aviation or ship materials (such as an instrument of a hydraulic system,a screw, an engine, and a turbine), materials for chemical industry(such as a ball, a gate, a plug, and a check), various dies, a machinetool part, and a vacuum apparatus part. The copper electroplating methodof the present invention is preferably used for the materials forelectronic industry, in which a particularly fine pattern is required,is more preferably used in the manufacture of, among the materials, asemiconductor package and a printed board typified by TSV formation,bump formation, and the like, and is most preferably used in thesemiconductor package.

EXAMPLES

Now, the present invention is described in more detail by way of theExamples and the Comparative Examples. However, the present invention isby no means limited by the following Examples and the like.

Examples 1 to 9

Sulfuric acid, the component (B), copper sulfate pentahydrate,hydrochloric acid, SPS, PEG4000, and water were mixed so as to givecompositions shown in Table 1 to obtain Example copper plating solutions1 to 9. The balance in each of the compositions of the copper platingsolutions shown in Table 1 was water, and the concentration of eachcomponent was adjusted with water. In addition, SPS (manufactured byTokyo Chemical Industry Co., Ltd.) and PEG4000 (manufactured by ADEKACorporation) used in the Examples are disodium3,3′-dithiobis(1-propanesulfonate) and polyethylene glycol having aweight-average molecular weight of from 3,600 to 4,400, respectively.

Plating baths of Examples and Comparative Examples shown in Tables 1 and2 below all had a pH of from 0 to 1.

TABLE 1 Example Hydrogen copper Component Component (B) Componentchloride SPS PEG4000 plating bath (A) (g/L) (concentration) (C) (g/L)(mg/L) (mg/L) (mg/L) Example 1 180 Compound 50 50 10 1,000 No. 7 (10g/L) Example 2 180 Compound 50 50 10 1,000 No. 7 (30 g/L) Example 3 180Compound 50 70 10 1,000 No. 7 (50 g/L) Example 4 180 Compound 30 50 101,000 No. 7 (3 g/L) Example 5 130 Compound 50 30 10 1,000 No. 7 (25 g/L)Example 6 130 Compound 50 50 10 1,000 No. 7 (5 g/L) Example 7 130Compound 60 50 10 1,000 No. 7 (1.5 g/L) Example 8 180 Compound 50 30 101,000 No. 8 (30 g/L) Example 9 180 Compound 50 50 10 1,000 No. 2 (10g/L)

Comparative Examples 1 to 8

Sulfuric acid, the component (B) or another component, copper sulfatepentahydrate, hydrochloric acid, SPS, PEG4000, and water were mixed soas to give compositions shown in Table 2 to obtain Comparative copperplating solutions 1 to 8. The balance in each of the compositions of thecopper plating solutions shown in Table 2 was water, and theconcentration of each component was adjusted with water. In addition,SPS and PEG4000 used in Comparative Examples are disodium3,3′-dithiobis(1-propanesulfonate) and polyethylene glycol having aweight-average molecular weight of from 3,600 to 4,400, respectively.Comparative compounds 1 to 5 used as the other components are compoundsshown below.

TABLE 2 Comparative Hydrogen copper Component Component (B) Componentchloride SPS PEG4000 plating bath (A) (g/L) (concentration) (C) (g/L)(mg/L) (mg/L) (mg/L) Comparative 180 Compound 50 50 10 1,000 Example 1No. 7 (0.1 g/L) Comparative 180 Compound 50 50 10 1,000 Example 2 No. 7(100 g/L) Comparative 180 Comparative 50 50 10 1,000 Example 3 compoundNo. 1 (10 g/L) Comparative 130 Comparative 50 50 10 1,000 Example 4compound No. 2 (10 g/L) Comparative 180 Comparative 50 30 10 1,000Example 5 compound No. 3 (5 g/L) Comparative 180 Comparative 70 50 101,000 Example 6 compound No. 4 (10 g/L) Comparative 180 Comparative 5050 10 1,000 Example 7 compound No. 5 (10 g/L) Comparative 180 None 50 5010 1,000 Example 8

Evaluation Examples 1 to 9 and Comparative Evaluation Examples 1 to 8

A paddle stirring-type plating apparatus was used as a copperelectroplating apparatus, and the plating tank of the paddlestirring-type plating apparatus was filled with each of the copperelectroplating solutions of Examples 1 to 9 and Comparative Examples 1to 8. A substrate to be plated was immersed in each of the copperelectroplating solutions. A product obtained by forming a resist pattern(shape: having an opening portion of a circular sectional shape, openingdiameter: 75 μm) on a Si substrate with a copper seed layer through useof a photoresist was used as the substrate to be plated. Next, copper ofeach copper electroplating solution was filled in the opening portion ofthe resist under the following plating conditions by a copperelectroplating method. Thus, a copper layer was formed on the substrateto be plated.

(Plating Conditions)

(1) Hole diameter: 75 μm

(2) Current density: 18 A/dm²

(3) Liquid temperature: 35° C.

(4) Plating time: A time period required for the minimum level (L_(Min))of a copper layer to become 40 μm

A minimum level 3 (L_(Min)) and a maximum level 4 (L_(Max)) of a copperlayer 1 formed on the surface of a substrate 2 to be plated by each ofEvaluation Examples 1 to 9 and Comparative Evaluation Examples 1 to 8 asillustrated in FIG. 1 were measured by observing a section of the copperlayer 1 with a laser microscope (manufactured by Keyence Corporation,model number: VK-9700), and ΔL was calculated from the followingequation. In addition, the content of organic residues in the obtainedcopper layer was measured by secondary ion mass spectrometry.

ΔL=L _(MAX) −L _(MIN)

TABLE 3 Copper Organic electroplating ΔL residue bath (μm) (ppm)Evaluation Example 1 Example 1 2 Undetectable Evaluation Example 2Example 2 2 Undetectable Evaluation Example 3 Example 3 5 UndetectableEvaluation Example 4 Example 4 4 Undetectable Evaluation Example 5Example 5 5 Undetectable Evaluation Example 6 Example 6 3 UndetectableEvaluation Example 7 Example 7 5 Undetectable Evaluation Example 8Example 8 6 Undetectable Evaluation Example 9 Example 9 3 UndetectableComparative Comparative 15 15 Evaluation Example 1 Example 1 ComparativeComparative 14 15 Evaluation Example 2 Example 2 Comparative Comparative14 20 Evaluation Example 3 Example 3 Comparative Comparative 16 15Evaluation Example 4 Example 4 Comparative Comparative 14 25 EvaluationExample 5 Example 5 Comparative Comparative 17 20 Evaluation Example 6Example 6 Comparative Comparative 15 15 Evaluation Example 7 Example 7Comparative Comparative 20 Undetectable Evaluation Example 8 Example 8

In Table 3, a smaller value of ΔL means that a copper layer that wasmore excellent in surface flatness was able to be formed. In addition, asmaller value of the “Organic residue” means that a copper layer thathad a higher purity was able to be formed. It was found from the resultsof Table 3 that in each of Evaluation Examples 1 to 9, a copper layer,which had a small content of the organic residues and was excellent insurface flatness as compared to those of Comparative Evaluation Examples1 to 7, was able to be formed. In particular, it was found that in eachof Evaluation Examples 1 and 2, a copper layer that was particularlyexcellent in surface flatness was able to be formed. In ComparativeEvaluation Example 8, the organic residues were not detected, but thevalue of LL was large, and a copper layer that was excellent in surfaceflatness could not be formed.

As described above, it was found that when a copper layer was formed onthe substrate to be plated by the copper electroplating methodcomprising using the copper electroplating solution of the presentinvention, a copper layer that had a high purity and was excellent insurface flatness was able to be formed.

REFERENCE SIGNS LIST

1 copper layer, 2 substrate to be plated, 3 minimum level (L_(MIN)), 4maximum level (L_(MAX)), 5 ΔL.

1. A copper electroplating solution, comprising the followingcomponents: (A) a sulfate ion; (B) a compound represented by thefollowing general formula (1); and (C) a copper ion, wherein the copperelectroplating solution has a content of the component (B) of from 0.3part by mass to 50 parts by mass and a content of the component (C) offrom 5 parts by mass to 50 parts by mass with respect to 100 parts bymass of a content of the component (A):

where R¹ and R² each independently represent a hydrogen atom, a sodiumatom, a potassium atom, or an alkyl group having 1 to 5 carbon atoms,and “n” represents 1 or
 2. 2. The copper electroplating solutionaccording to claim 1, wherein the R¹ represents a hydrogen atom, asodium atom, or a potassium atom, and the R² represents a hydrogen atom.3. The copper electroplating solution according to claim 1, furthercomprising a chloride ion.
 4. The copper electroplating solutionaccording to claim 1, wherein 1 L of the copper electroplating solutioncomprises 10 g to 500 g of the component (A).
 5. A copper electroplatingmethod, comprising using the copper electroplating solution of claim 1.6. A method of producing a copper electroplating solution, comprisingmixing a sulfate ion supply source, a compound represented by thefollowing general formula (1), a copper ion supply source, and asolvent, wherein the copper electroplating solution has a content of thecompound represented by the general formula (1) of from 0.3 part by massto 50 parts by mass and a content of a copper ion of from 5 parts bymass to 50 parts by mass with respect to 100 parts by mass of a contentof a sulfate ion:

where R¹ and R² each independently represent a hydrogen atom, a sodiumatom, a potassium atom, or an alkyl group having 1 to 5 carbon atoms,and “n” represents 1 or
 2. 7. The method of producing a copperelectroplating solution according to claim 6, wherein the R¹ representsa hydrogen atom, a sodium atom, or a potassium atom, and the R²represents a hydrogen atom.
 8. The method of producing a copperelectroplating solution according to claim 6, wherein 1 L of the copperelectroplating solution comprises 10 g to 500 g of the component (A).